SAVANNAH, Georgia (CNN) -- Heads of the world's leading economic powers have began gathering in the U.S. state of Georgia for their annual G8 summit, where Iraq is dominating discussions.

The mood at the gathering on Tuesday was buoyed by news that the U.N. Security Council approved a new resolution setting out the framework for the political and security transition of Iraq -- a breakthrough on an issue that had frayed relations among the G8 partners.

"The vote today in the United Nations Security Council was a great victory for the Iraqi people," Bush said with Russian President Vladimir Putin at his side. (Full story)

"The international community showed it stands side-by-side with the Iraqi people ... America supports strongly the idea of a free society in the midst of hatred and intolerance," Bush said.

Putin called the resolution a "major step forward."

While the summit won't formally begin until Wednesday, its host, Bush, held one-on-one meetings Tuesday afternoon with four of his counterparts -- Putin, Japanese Prime Minister Junichiro Koizumi, Canadian Prime Minister Paul Martin and German Chancellor Gerhard Schroeder.

"I must say that I do believe that the mood at this G8 summit is going to be really one that's going to be very constructive, and I think that the U.N. resolution is certainly going to be part of that," Martin said.

Bush thanked Martin for Canada's cooperation in the war on terror.

"The prime minister has got a clear vision about the dangers that face the free world and for that I'm grateful to him," said Bush during an afternoon news conference held by the two leaders.

"We are all in peril here and we have all got to win this war," said Martin. "Canada certainly intends to do our part and we stand with you four-square in the battle against global terrorism."

Bush, emerging from lunch with Koizumi where North Korea was high on the agenda, said the resolution would help ensure "our objective is achieved."

"These nations understand that a free Iraq will serve as a catalyst for change in the broader Middle East, which is an important part of winning the war on terror," he said before the measure was passed.

Also attending the summit -- where the global economy, trade and fighting poverty will also feature -- are British Prime Minister Tony Blair, Italian Prime Minister Silvio Berlusconi and French President Jacques Chirac.

The Group of Eight includes Canada, France, Germany, Italy, Japan, Russia, the United Kingdom and the United States. Two representatives of the European Union -- Irish Prime Minister Bertie Ahern and Romano Prodi, president of the European Commission -- will also participate. Ireland currently holds the EU's rotating presidency. (Interactive: A G8 explainer)

Schroeder, speaking to reporters after meeting with Bush, said the economic and security discussions at the summit will be intertwined.

"I think what we're talking about here at this meeting will be essentially something that, indeed, forms part of one whole and something that is indissoluble -- namely, a good world economy on the one hand and a stable political environment on the other," Schroeder said.

Schroeder, along with Chirac and Putin, actively opposed the U.S.-led Iraq war, which was strongly supported by Blair and Berlusconi. Japan contributed forces to post-war Iraq, while Canada did not participate in either the war to topple Saddam Hussein or the occupation.

The U.S. president will meet Wednesday with the new Iraq leader, President Ghazi al-Yawer. (Full story)

Throughout Tuesday, G8 leaders were given red-carpet ceremonial welcomes at Hunter Army Airfield in Savannah, about 80 miles north of the summit site on Sea Island, a secluded enclave accessible from the mainland by a single causeway.

Security is extremely tight for the summit. Sea Island itself is closed to all but summit participants. Neighboring St. Simons Island, a popular resort, remained open, but organizers warned visitors of possible security checks. Members of the media were being housed in Savannah, well away from the summit site.

"We are a nation at war. We are a world that is under threat by terrorists," White House communications director Dan Bartlett said Tuesday. "To have that many world leaders to come together is a unique security threat that we have to take very seriously."

Previous global summits have been disrupted by sometimes violent demonstrations by anti-globalization activists. At this year's G8, protests are being limited to the city of Brunswick, on the mainland side of the causeway.

A protest march Tuesday morning drew only about 200 demonstrators and went off without incident. (Full story)

The G8 summit, which rotates among participating nations, was last held in the United States in Denver in 1997. The tone of this year's meetings was designed to be informal, with leaders shedding their coats and ties at the seashore.

The summit comes three days after D-Day commemorations in France, and just before this month's NATO summit in Istanbul, Turkey. One expert says Washington will want to put the United States in a more positive light.

"It is very much a pre-election G8," said Katynka Barysch, an analyst at the Center for European Reform.

"You can see it very clearly, the U.S. trying to highlight topics that make the U.S. look more in a conciliatory mood on the global stage," Barysch said. (Gallery: Summit security)

This year terrorism and its likely impact on world oil prices will see the European leaders lining up with the U.S. in common concern, according to Barysch.

"They might not be so reliant on cheap oil as the American economy is but they obviously have a very high stake in the world economy picking up. So they will want to talk about oil," said Barysch.